Field of the Invention
The present invention relates to a quartz crystal vibrator and a manufacturing method thereof.
Description of the Related Art
In general, a vibration piece using quartz crystal may obtain a high frequency and has stable frequency characteristics, such that the vibration piece has been used in reference frequency sources, oscillation sources, for example, of various electronic devices. To this end, a quartz crystal piece is made of quartz gemstone in a direction suitable for characteristics, and this quartz crystal piece is used as a vibrator, as a non-limiting example.
Among them, an AT-cut quartz crystal substrate is cut so that a surface thereof obtained by rotating a plane including X and Y axes of a quartz crystal along a circumference of the X axis at an angle of about 35° 15′ in a counterclockwise direction from the X axis becomes a main surface, and the vibration piece using the AT-cut quartz crystal substrate has been widely used in a mobile communications terminal, for example, due to excellent frequency-temperature characteristics.
However, in an AT-cut quartz crystal substrate according to the convention art, as described, for example, in U.S. Pat. No. 8,581,476, at the time of processing a side surface, a wet etching method has been used, but a sequence of an expressed plane is changed depending on the kind of etching solution and a temperature, an etched surface is not vertical to a flat main surface but has an obliquely inclined shape, and various planes are expressed, such that it is impossible to implement a precise element.